About two years into the project thus far. (Cannot upload pix or link here yet, am very new, but many thanks @obi_waynne , for the invite to post this.) Negative ion generators are lately quite common in air conditioners, air cleaners, and other devices; these charge millions of air molecules negatively, and the results are helpful in a few ways. The most proven ways are "clumping" of dust particles for filtration efficiency and destruction of many aromatic esters (a.k.a. unpleasant smells), but many people have been more or less unscientifically claiming health benefits, due to the "invigoration" one feels of negatively charged air after a thunderstorm. Anyway, I used these things to destinkify an unpleasant basement for a few...